Abstract The widespread use of magnesium alloys in applications that require high specific strength and stiffness has been hindered by its relatively low ductility. The hexagonal close-packed crystalline structure of magnesium alloys causes strong anisotropy in the mechanical response, which is reasonably well understood; however, the failure behavior is more complex. It is not clear whether the plastic anisotropy or the existence of second phase particles control failure, and to date, more attention has been given to the former than the latter. In this work, a series of high-rate tension experiments were performed on thin foil specimens of hot rolled magnesium alloy AZ31B using a miniaturized tensile Kolsky bar along an array of angles in the normal-rolling plane at strain rates of nominally 10 4 s − 1 . These experiments are compared with a set of finite element computations employing crystal plasticity and direct numerical simulation of void-nucleating second phase particles measured using micro-CT. Simulations are used to quantify the relative role that plastic anisotropy and second phase particle morphology play in dictating the failure response of rolled magnesium. Results indicate that plastic anisotropy dictates the way that voids grow and coalesce, and that in some cases, the pronounced plastic anisotropy of magnesium increases, rather than decreases, the maximum strain to failure. In all cases, the large second phase particles in rolled magnesium AZ31B greatly reduce the maximum failure strain as compared with an equivalent volume fraction of randomly distributed spherical particles. Additionally, it is shown that simulations lacking a proper description of orientation-dependent plastic anisotropy and particle morphology do not correlate well with measured failure behavior.

中文翻译：

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轧制镁的动态拉伸破坏：量化织构和第二相颗粒作用的模拟和实验

摘要 镁合金在需要高比强度和刚度的应用中的广泛使用受到其相对较低的延展性的阻碍。镁合金的六方密堆积晶体结构在机械响应中引起强烈的各向异性，这是很好理解的；然而，故障行为更为复杂。目前尚不清楚是塑性各向异性还是第二相粒子的存在控制失效，迄今为止，前者比后者更受关注。在这项工作中，使用微型拉伸 Kolsky 棒沿着法向轧制平面中的一系列角度，以名义上 10 4 s 的应变速率对热轧镁合金 AZ31B 的薄箔试样进行了一系列高速拉伸实验 - 1 . 这些实验与一组有限元计算进行了比较，这些计算采用晶体塑性和使用微 CT 测量的空隙成核第二相粒子的直接数值模拟。模拟用于量化塑性各向异性和第二相颗粒形态在决定轧制镁的失效响应中所起的相对作用。结果表明，塑性各向异性决定了空隙生长和聚结的方式，并且在某些情况下，镁的显着塑性各向异性会增加而不是减少最大失效应变。在所有情况下，与随机分布的球形颗粒的等效体积分数相比，轧制镁 AZ31B 中的大第二相颗粒大大降低了最大破坏应变。此外，